Cracking with hydrogen fluoride catalyst



Aug. 15, 1950 R`.J.HENGsTEBr-:CK

l CRACKING WITH HYDROGE'N FLUORIDE CATALYST Filed Nov. 9, 194e LOK Patented Aug. 15! 1950 [OF FI CE 1GRAICKING WITH HYDROGEN-ELU'ORIDE f lGA'IALYST Y r, Robert; J. Hengstebeck, Chicago; I1l.,.` assignor- 'to "'Standaril Oil yCompany, IfGhieagQ, Ill., ;a corporation Vof Indiana ,tApplicationNovember 9, 1946, SerialNo.' 708,999 10mm. (c1. Y1116-1-52) Y i1 i .This invention relates, .to aprocess4 of converting hydrocarbon voils and .morev particularly to a process and apparatusfor converting` heavy oils rinto Vgasoline;light hydrocarbon .disti11ates andltar, bythe action; of hydrouoric acid cata- "One object ofthe :invention is toeffect the conversionsof hydrocarbons rby" the action'of HF in aneconomical and satisfactory manner. n.Anjother -object of the invention .toY recycle HF sludge thru fthe conversion zoneswhile simultaneously withdrawing-4 al regulated-portion of the YHF,sludge and recovering ,HF therefrom for further-'use inthe conversion reaction. Still another phj-ect of `:the l 'invention -is` torecover- HF from the; gasoline produ'ctsfina simple, economievand eiectve-manner as fwill be `more fullydescribed hereinafter. The inventionjis; illustratedl ,byk a vdrawingwhich showsdiagrammatically an apparatusfor suitably carrying out the process, y

"'Qne othe fdifliculties in effecting conversion of hydrocarbons by the' actionof HF lies-inrecovery of Athe HF ifrom'. the v:various stocks produced in, the process. 'Becauseof the'relatively highvapor pressure-of HF it is found` distributed in, all ystocks produced in the process -extending allj-theway .from the heavy :'tar'toi the xed gases. `torecoverit. by water absorption ,inasmnchas 'the aqueous solutions; of HF'are `very corrosive and therefore," difficult to ,handle and; because the recovejryof` anhydrous from aqueous solutions fisa'costly'operation. By the use of my process the HF catalyst;` isf-,substantially allreturned to the conversion reaction without fthe necessity of Yrecovering#itvfrom aqueous solutions.

y stock employedis usuallyaheavyparairlnic distillate oil suchy as gas foil;-` kerosene; etc. l oriheavy distillati-es @from v carbon 'monoxide `synthesis. Otherlstocksf-however, Amaybe'treated suchf as parafn wax, reduced crude,1=arid,less' desir-ably, heavy distillates from I' cradkingf processes; particuarlygas cil' from catalytic cracking# employ- -ing vsiliceous cat'aiysts. HGa-s oils 'from 'LMid- Continent `rand Westillexas umide oil are :particularly suitablef-stocks for treating" lbyv my process, as are also the more"parainic-heavyfdistillates Ity isv furthermore highly Yimpracticable f 'from' Pennsylvania; Michigan and Illinois crude oils.

1 Heater 120; may suitably be a pipe still andI prefer to heat the charging stock therein to a temperature of about. i700 to`750 F. In theoperationfoffmy process, it isdesirable to eliminate Water from Wthe -hydro`carbon stock as` far as economically: 'possible and thisl maybe accomplishedlzin severalaways, Thus in gas separator 1l li. Water'vapor and.- gasy are. discharged` by line 21.. 'f'ltheainount of `water l'eft inthe oil is still excessivewthe chargingoil stream may be passed by valvedline22 toash tower-23 wherer the hot -oil''ilows downwardly passing out byvalved line l2111.:at,thetb'ottom. Suicientvpressure is maintainediinxtoweri23 to preventv vaporization of all butaafsmall portion vofvthe oil, and the vapors proxiccediare.eonductedbyline` 25 to condenser 'ZB-andreceiverf 21. -Here theY condensate is collectexandawater is :permitted to separate at the bottom feromfwhich it is removed by valved line fwhi'le the oil collecting in2'i ows by line 29 in'rqmrnpifllandi'line3|y back to ltower 23. A lsmalh ambunttof. `watercarried back' to the tower inssontion Land/or v`entrained in the returned streamrzthruyalved line 3l can `be removed by aternatively passing the oil from* pump` 30` thru drying :chambers 32,*so that substantially every strane ,bfwater is` removedl before returning` to ftower. l if 'thehydrocarbon stock is suiciently dehydrated before charging to heater 20, it'may be conducted directlyby valve 33 and valved line Stifte he'ati ex'changer35 where' the heatedeed stock niserves` to"pr'ovide heatfor Vthe operation ofizfi'actionatingcolumn 36 as hereinafter described. i'ln"` heatexchanger 3'5 the temperature ofi fthe; oil-'maybe dropped" from` a point; `within the range of about 700 to '750 F. to a point'withvinfl'flfiearange of about 500 lto60(l"l. `'I'l'ie-"zfeed stockthen flows by 1ine-31 rto heat exchanger 38 Iwheres-heatis 'supplied Ifor theA operation" afdepropanirng tower" 39- as hereinafter described. Thexfeedf stock now! n at a temperature ofabout to' 500'FsoWs by liney andcharge pump il towreactorf-M. 'The temperature in reactor lxmay beabouti'ZG fto 460 F., preferably about 3W the temperature dbeing Aobtained primarilylzby -controliing ythe temperature of the Yhot oil feed.

Hydrouoriclacid catalyst is introducedI bylne `llsclireetly :intothe eedol stream in line lll or injecteddirectly into reactor 42 if desired. lIn reactor 42, intimate `contact isV obtained between the HE-whichfispresent largely *bhefliriuidmhase andthezhydrocarbon oil.""1he 4 39 are passed by vapor line 12 to condenser 13 and thence by line 14 to receiver 15 wherein the liquid propane fraction separates as an upper layer from HF. A portion of the propane layer is returned to fractionator 39 as a reux by pump 16 and line 11 while the lower HF layer flows by valved line 18 to HF drum 68 and thence back to the reactor by line 69, pump and line 1| as hereinbefore described. The uncondensed gases and excess propane from receiver are conducted by line 19 to wash tower 80 for removal of actor 42 can be facilitated by the use of bailles 44 Y and by recycling the reaction mixture by line'45 and pump 46. ployed also. The time of contacting, i. e. the average residence time of the oil, in reactor 42 is suitably about 1 to 60 minutes, depending on the catalyst-oil ratio, the temperature and character of the stock treated. The pressure employed is preferably sumcient to keep the HF in liquid phase, a pressure of about 500 to 5000 p. s. i. defining a suitable range. When operating at 300 F. to 350 F., a pressure of about 850 p.s. i. is satisfactory.

From reactor 42 the reaction mixture flows by line 41 to receiver 48 usually maintained under full reactor pressure and substantially at reactor temperature or somewhat below but without agitation. By reducing the pressure in line 41 by a moderate amount, e. g. from '100 p. s. i. to 500 p. s. i., a portion of the lighter products and HF is flashed in 4.8 with corresponding reduction in temperature, e. g. from 300 to 200-250" F. In the receiver` 48 the reaction mixture separates into two layers, the upper layer consisting subl 50 whereby it is recycled back tothe reactor. q1

Inasmuch as the catalyst phase or lower layer in separator 48 contains most of the tar produced in the process, it is necessary to withdraw a portion of it continuously or periodically to .remove tar from the system. This is effected by conducting the catalyst phase thru pressure-reducing valve 5| in line 52 and heater 53 and thence to flash drum 54 where the pressure is maintained near atmospheric, e. g. 20 p. s. i. The vapors liberated, comprised mostly of. HF and light hydrocarbons, are conducted by line 55 to condenser 55 whence the HF flows by line 51 to receiver 58 from which the liquid HF is withdrawn by pump 59 and forced by line |50 into the hot feed oil in line 10. Light hydrocarbons separating in 58 may be withdrawn by line 58a and,

if desired, charged to depropanizer 39 for sta-Y 83 thru reducing valve E4 into depropanizer 39.

Here the stocks are fractionated by heat supplied from 38 thru trapout recycle lines 85 and G6, the HF is condensed in the top of the fractionator and is trapped out with some butanes by lineY 61 leading to HF trapout drum 68, whence the liquid HF and butanes associated therewith are conducted byline 69 and pump 19 back to reactor 42, usually by injecting the stream directly into the hot oil feed stream by line 1|.

The vapors from the top of depropanizer tower Mechanical agitators can be em- HF as hereinafter described.

Any Xed gases produced in the process such as methane and ethane, together with a small amount of propane which separate in separator 48, are conducted by line 8| to tower 82 where they are cooled by a stream of reflux which serves to condense the major part of the HF vapor contained therein. The HF condensate together with some hydrocarbons is withdrawn by pump 83 andconducted by line 84 back to separator 48 or to the transfer line leading thereto.

Y From the top of gas separator 82 the gases flow by line 85 to cooler 86 and reflux drum 81 from which a liquid fraction comprised principally of HF and propane is returned to the tower by line 88 for reflux. The uncondensed gases pass from the top of receiver 81 thru line 89 and pressure-reducing valve 90 into wash tower 80.

Fump 93 serves to recirculate the water or other absorbent [liquid back to the tower. From time to time or continuously excess wash solution may be withdrawn by valved line 94 and treated to recover dissolved I-lllA which may be returned to the conversion system after dehydration. Washed hydrocarbon gases are withdrawn from the top of tower 89 by line 95 and may be discharged from the system by valved line 96 or given a further water-washing in wash tower 91 before discharging thru line 98.

The depropanized oil product containing tar, lgasoline and unconverted hydrocarbons is withdrawn from the base of tower 39 by line |00 which conducts it to debutanizer tower |0| supplied by heat from trapout heater |02. Vapors from the top of tower |0| are withdrawn by line |03, condensed in condenser |04, and thence collected in reflux drum |05 from which pump-back is withdrawn byV pump |06 to provide reflux for the tower by line |01. Uncondensed gases and ex- 'cess butanepass from receiver |05 by line |08 to butane wash tower |09 where the butane is washed to remove any trace of HF remaining in it, water being supplied for this purpose by line ||0. This water may have been previously ernployed in wash tower 91. It is recycled from wash tower |09 by pump in valved line ||2. As the concentration of HF in wash water in line l2 increases it is Withdrawn continuously or intermittently'by valved line |3 for use in wash If desired, a heavy oil fraction, for example gas oil, can be trapped out from tower 36 by valved line |23 and pump |24 which discharges it into feed line 31 for recycle to the conversion step of the process. The bottomsfrom fractionator 35 herein referred to as tar are withdrawn by line |25 leading to heat exchanger l5 and thence by pump |26 and line |21 thru cooler |28 where the temperature is dropped to about 150 F. Cooled tar is discharged from the system by line |29.

One of the advantageous features of my process of HF cracking is the recovery of HF in the anhydrous condition suitable for re-use in the process Without expensive dehydration. All the HF removed from the product by distillation in tower 39 is condensed and recycled excepting that portion which is carried out of the liquid hydrocarbon gases collected in receiver 15. In removing the light fractions from the products in fractionator 39, a substantial amount of HF is conduct-ed overhead with the hydrocarbon gases as an azeotrope. On condensation of the hydrocarbons, however, the major part of the HF therein separates as a liquid layer in the receiver and is returned to the system by line 18 as previously indicated.

The combined treatment of tar and other liquid hydrocarbon products in fractionators 39, |0| and 36 offers the advantage of simplifying the recovery of HF therefrom by maintaining the tar in solution in the lighter hydrocarbon products, thus facilitating its handling and facilitating HF recovery from tar at -lower temperatures owing to the effect of gasoline vapors in removing HF Vfrom the tar complex. On passing the products thru the depropanizer and the debutanizer, the substantially complete removal of HF is effected.

Having thus described my invention what I claim is:

The method of converting a hydrocarbon oil higher boiling than gasoline into products consisting chiefly of gasoline and tar, which method comprises intimately contacting said oil with a catalyst consisting of hydrogen fluoride at a temperature in the range of 200 to 400 F. with a catalyst to oil weight ratio in the range of .2:1 to 4:1, the low ratios in this range being employed with high temperatures in the temperature range and vice versa, at a pressure suflicient to maintain liquid phase conversion conditions and for a time of contact in the range of 1 to 60 minutes and sufficient to obtain substantial conversion of the oil into gasoline, gases and tar, introducing conversion products and catalyst into a settling zone maintained at high pressure, withdrawing gas from the upper part of the settling zone to a gas-liquid separation zone cooled at its upper end, returning separated liquid to said settling zone,

gelati@ withdrawing separated hydrogen fluoride-insoluble oil from the settling zone, reducing its pressure to that of a depropanizing zone and introducing it into said depropanizing zone, separately withdrawing a hydrogen uoride-tar stream from the settling zone, reducing its pressure to about atmospheric to 20 pounds per square inch gauge, heating it and introducing it into a flash Zone and flashing the bulk of the hydrogen fluoride therefrom in said flash zone, condensing the hydrogen fluoride removed by flashing in the flash zone and returning it to the contacting step, pumping the tar from' the flash zone under increased pressure to the depropanizing zone, stripping residual hydrogen fluoride from the combined tar and hydrogen fluoride-insoluble oil in the depropanizing zone whereby the presence of light hydrogen fluoride-insoluble oil facilitates removal of substantially all hydrogen fluoride from the tar, withdrawing a, liquid light hydrocarbon-hydrogen fluoride stream from an intermediate part of the depropanizing zone, separating hydrogen fluoride from the withdrawn stream and returning the separated hydrogen fluoride to the contacting step, cooling the stream of gases withdrawn from the upper part of the depropanizing zone and introducing the cooled stream into a receiving zone, combining gases from the receiving zone with gas from the gas-liquid separation zone, removing hydrogen uoride from the combined gases, and fractionating the stripped mixture of tar and hydrogen fluoride-insoluble oil into a plurality of fractions including a gasoline fraction and a tar fraction.

ROBERT J. HENGSTEBECK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,322,800 Frey June 29, 1943 2,372,338 Penisten Mar. 27, 1945 2,378,636 Iverson June 19, 1945 2,379,368 Matuszak June 26, 1945 2,388,156 Kelley Oct. 30, 1945 2,392,962 Abrams et al Jan. 15, 1946 2,403,650 Frey July 9, 1946 2,405,993 Burk Aug. 20, 1946 2,417,875 Leonard Mar. 25, 1947 2,426,273 Johnstone Aug. 26, 1947 2,427,009 Lien et al Sept. 9, 1947 2,434,040 Hartman Jan. 6, 1948 2,436,695 Kuhn Feb. 24, 1948 OTHER REFERENCES Linn et al.: Ind. Eng Chem., vol. 37, No. 10, October 1945, pages 924-929. 

